Studies of kinetic control of production of activated coagulation factors of the tissue factor and extrinsic pathways continue. Purification and chemical and immunological characterization of the tissue factor molecule is proposed, as well as definition of control of this activity in cultured cells. BIBLIOGRAPHIC REFERENCES: Pitlick, F.A. 1976, Binding of Bovine Brain Tissue Factor to Concanavalin A-Sepharose Partial Purification of Coagulant, Arylamidase, and Alkaline Phosphatase Activities. Biochim. Biophys. Acta 428:27-34. Stemerman, M.B., Pitlick, F.A., and Dembitzer, H.M. 1976, Electron Microscopic Immunohistochemical Identification of Endothelial Cells in the Rabbit. Circ. Res. 38:146-156.